Copyright (c) 2016-present, RxJava Contributors.
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
compliance with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software distributed under the License is
distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
the License for the specific language governing permissions and limitations under the License.
/**
 * Copyright (c) 2016-present, RxJava Contributors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is
 * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
 * the License for the specific language governing permissions and limitations under the License.
 */

package io.reactivex.internal.operators.completable;

import java.util.concurrent.Callable;

import io.reactivex.*;
import io.reactivex.disposables.Disposable;
import io.reactivex.exceptions.Exceptions;

public final class CompletableToSingle<T> extends Single<T> {
    final CompletableSource source;

    final Callable<? extends T> completionValueSupplier;

    final T completionValue;

    public CompletableToSingle(CompletableSource source,
            Callable<? extends T> completionValueSupplier, T completionValue) {
        this.source = source;
        this.completionValue = completionValue;
        this.completionValueSupplier = completionValueSupplier;
    }

    @Override
    protected void subscribeActual(final SingleObserver<? super T> observer) {
        source.subscribe(new ToSingle(observer));
    }

    final class ToSingle implements CompletableObserver {

        private final SingleObserver<? super T> observer;

        ToSingle(SingleObserver<? super T> observer) {
            this.observer = observer;
        }

        @Override
        public void onComplete() {
            T v;

            if (completionValueSupplier != null) {
                try {
                    v = completionValueSupplier.call();
                } catch (Throwable e) {
                    Exceptions.throwIfFatal(e);
                    observer.onError(e);
                    return;
                }
            } else {
                v = completionValue;
            }

            if (v == null) {
                observer.onError(new NullPointerException("The value supplied is null"));
            } else {
                observer.onSuccess(v);
            }
        }

        @Override
        public void onError(Throwable e) {
            observer.onError(e);
        }

        @Override
        public void onSubscribe(Disposable d) {
            observer.onSubscribe(d);
        }

    }
}